The present invention relates to a method and apparatus for winding a continuously advancing yarn to a package, and of the general type disclosed in EP 0 235 557 and corresponding U.S. Pat. No. 4,913,363.
When winding a yarn to a cross-wound package, the yarn is deposited at a crossing angle on the package surface within the package width at a substantially constant circumferential speed of the package. To this end, the yarn is reciprocated by a traversing yarn guide within a traverse stroke, before it contacts the package surface. To obtain a uniform mass distribution of the yarn, in particular in the edge regions of the package, it is known to shorten and lengthen the traverse stroke cyclically during the winding. This shortening and lengthening of the traverse stroke is named a so-called stroke modification. The stroke modification prevents a high edge buildup (saddle formation) of the packages.
In the method known from the above cited prior patents, the stroke modification occurs in predetermined modified stroke cycles. A modified stroke cycle is defined by the period of time, which is required for reaching again the length of the traverse stroke that has been adjusted before the stroke modification. Thus, a modified stroke cycle is formed by a plurality of modified strokes, which define one reciprocal movement of the traversing yarn guide at a modified length of the traverse stroke length. Thus, when passing through a modified stroke cycle, the yarn is deposited on the package surface in many modified strokes. The beginning of the modified stroke cycle may thus be removed from the end of the modified stroke cycle by a plurality of yarn layers. In this connection, there exists the problem that the yarns deposited at the outer edge of the package, i.e. at a maximum traverse stroke, are deposited before and after the modified stroke cycle in the same place on the circumference of the package, which leads to undesired double layers.
It is therefore an object of the invention to provide a method of the initially described kind as well as an apparatus for carrying out the method, which makes it possible to wind a cross-wound package with substantially evenly distributed yarn reversal points in the end regions of the cross-wound package.